/*
 *
 * Copyright 2015-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may
 * obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
 * and limitations under the License.
 *
 *
 */

package springfox.documentation.spring.web.readers.parameter;

import static com.google.common.base.Objects.equal;
import static com.google.common.base.Predicates.and;
import static com.google.common.base.Predicates.not;
import static com.google.common.base.Predicates.or;
import static com.google.common.base.Strings.isNullOrEmpty;
import static com.google.common.collect.FluentIterable.from;
import static com.google.common.collect.Lists.newArrayList;
import static com.google.common.collect.Sets.newHashSet;
import static springfox.documentation.schema.Collections.collectionElementType;
import static springfox.documentation.schema.Collections.isContainerType;
import static springfox.documentation.schema.Types.typeNameFor;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.util.ClassUtils;

import com.fasterxml.classmate.ResolvedType;
import com.fasterxml.classmate.members.ResolvedField;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.FluentIterable;

import springfox.documentation.builders.ParameterBuilder;
import springfox.documentation.schema.Maps;
import springfox.documentation.schema.Types;
import springfox.documentation.schema.property.field.FieldProvider;
import springfox.documentation.service.Parameter;
import springfox.documentation.spi.schema.AlternateTypeProvider;
import springfox.documentation.spi.schema.EnumTypeDeterminer;
import springfox.documentation.spi.service.contexts.DocumentationContext;
import springfox.documentation.spi.service.contexts.ParameterExpansionContext;
import springfox.documentation.spring.web.plugins.DocumentationPluginsManager;

//本类用于处理swagger对象嵌套内存溢出的问题
@Component
public class ModelAttributeParameterExpander {
    private static final Logger LOG = LoggerFactory.getLogger(ModelAttributeParameterExpander.class);
    private final FieldProvider fieldProvider;
    private final EnumTypeDeterminer enumTypeDeterminer;

    @Autowired
    protected DocumentationPluginsManager pluginsManager;

    @Autowired
    public ModelAttributeParameterExpander(FieldProvider fields, EnumTypeDeterminer enumTypeDeterminer) {

        this.fieldProvider = fields;
        this.enumTypeDeterminer = enumTypeDeterminer;
    }

    public List<Parameter> expand(ExpansionContext context) {

        List<Parameter> parameters = newArrayList();
        Set<String> beanPropNames = getBeanPropertyNames(context.getParamType().getErasedType());
        Iterable<ResolvedField> fields = FluentIterable.from(fieldProvider.in(context.getParamType()))
                .filter(onlyBeanProperties(beanPropNames));
        LOG.debug("Expanding parameter type: {}", context.getParamType());
        AlternateTypeProvider alternateTypeProvider = context.getDocumentationContext().getAlternateTypeProvider();

        FluentIterable<ModelAttributeField> modelAttributes = from(fields).transform(toModelAttributeField(alternateTypeProvider));

        FluentIterable<ModelAttributeField> expendables = modelAttributes.filter(not(simpleType())).filter(not(recursiveType(context)));
        for (ModelAttributeField each : expendables) { // 非基本类型
            LOG.debug("Attempting to expand expandable field: {}", each.getField());
            // 注释掉
//            parameters.addAll(
//                    expand(
//                            context.childContext(
//                                    nestedParentName(context.getParentName(), each.getField()),
//                                    each.getFieldType(),
//                                    context.getDocumentationContext())));
        }

        FluentIterable<ModelAttributeField> collectionTypes = modelAttributes
                .filter(and(isCollection(), not(recursiveCollectionItemType(context.getParamType()))));
        for (ModelAttributeField each : collectionTypes) { // 集合
            LOG.debug("Attempting to expand collection/array field: {}", each.getField());

            ResolvedType itemType = collectionElementType(each.getFieldType());
            if (Types.isBaseType(itemType) || enumTypeDeterminer.isEnum(itemType.getErasedType())) {
                parameters.add(simpleFields(context.getParentName(), context.getDocumentationContext(), each));
            } else {
                // 注释掉
//                parameters.addAll(
//                        expand(
//                                context.childContext(
//                                        nestedParentName(context.getParentName(), each.getField()),
//                                        itemType,
//                                        context.getDocumentationContext())));
            }
        }

        FluentIterable<ModelAttributeField> simpleFields = modelAttributes.filter(simpleType());
        for (ModelAttributeField each : simpleFields) {
            parameters.add(simpleFields(context.getParentName(), context.getDocumentationContext(), each));
        }
        return FluentIterable.from(parameters).filter(not(hiddenParameters())).toList();
    }

    private Predicate<ModelAttributeField> recursiveCollectionItemType(final ResolvedType paramType) {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return equal(collectionElementType(input.getFieldType()), paramType);
            }
        };
    }

    private Predicate<Parameter> hiddenParameters() {
        return new Predicate<Parameter>() {
            @Override
            public boolean apply(Parameter input) {
                return input.isHidden();
            }
        };
    }

    private Parameter simpleFields(String parentName, DocumentationContext documentationContext, ModelAttributeField each) {
        LOG.debug("Attempting to expand field: {}", each);
        String dataTypeName = Optional.fromNullable(typeNameFor(each.getFieldType().getErasedType()))
                .or(each.getFieldType().getErasedType().getSimpleName());
        LOG.debug("Building parameter for field: {}, with type: ", each, each.getFieldType());
        ParameterExpansionContext parameterExpansionContext = new ParameterExpansionContext(dataTypeName, parentName, each.getField(),
                documentationContext.getDocumentationType(), new ParameterBuilder());
        return pluginsManager.expandParameter(parameterExpansionContext);
    }

    // 递归类型
    private Predicate<ModelAttributeField> recursiveType(final ExpansionContext context) {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return context.hasSeenType(input.getFieldType());
            }
        };
    }

    @SuppressWarnings("unchecked")
    private Predicate<ModelAttributeField> simpleType() {
        return and(not(isCollection()), not(isMap()), or(belongsToJavaPackage(), isBaseType(), isEnum()));
    }

    // 集合类型
    private Predicate<ModelAttributeField> isCollection() {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return isContainerType(input.getFieldType());
            }
        };
    }

    private Predicate<ModelAttributeField> isMap() {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return Maps.isMapType(input.getFieldType());
            }
        };
    }

    private Predicate<ModelAttributeField> isEnum() {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return enumTypeDeterminer.isEnum(input.getFieldType().getErasedType());
            }
        };
    }

    private Predicate<ModelAttributeField> belongsToJavaPackage() {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return ClassUtils.getPackageName(input.getFieldType().getErasedType()).startsWith("java.lang");
            }
        };
    }

    private Predicate<ModelAttributeField> isBaseType() {
        return new Predicate<ModelAttributeField>() {
            @Override
            public boolean apply(ModelAttributeField input) {
                return Types.isBaseType(input.getFieldType()) || input.getField().getType().isPrimitive();
            }
        };
    }

    private Function<ResolvedField, ModelAttributeField> toModelAttributeField(final AlternateTypeProvider alternateTypeProvider) {
        return new Function<ResolvedField, ModelAttributeField>() {
            @Override
            public ModelAttributeField apply(ResolvedField input) {
                return new ModelAttributeField(fieldType(alternateTypeProvider, input), input);
            }
        };
    }

    private Predicate<ResolvedField> onlyBeanProperties(final Set<String> beanPropNames) {
        return new Predicate<ResolvedField>() {
            @Override
            public boolean apply(ResolvedField input) {
                return beanPropNames.contains(input.getName());
            }
        };
    }

    @SuppressWarnings("unused")
    private String nestedParentName(String parentName, ResolvedField field) {
        String name = field.getName();
        ResolvedType fieldType = field.getType();
        if (isContainerType(fieldType) && !Types.isBaseType(collectionElementType(fieldType))) {
            name += "[0]";
        }

        if (isNullOrEmpty(parentName)) {
            return name;
        }
        return String.format("%s.%s", parentName, name);
    }

    private ResolvedType fieldType(AlternateTypeProvider alternateTypeProvider, ResolvedField field) {
        return alternateTypeProvider.alternateFor(field.getType());
    }

    private Set<String> getBeanPropertyNames(final Class<?> clazz) {

        try {
            Set<String> beanProps = new HashSet<String>();
            PropertyDescriptor[] propDescriptors = getBeanInfo(clazz).getPropertyDescriptors();

            for (PropertyDescriptor propDescriptor : propDescriptors) {

                if (propDescriptor.getReadMethod() != null) {
                    beanProps.add(propDescriptor.getName());
                }
            }

            return beanProps;

        } catch (IntrospectionException e) {
            LOG.warn(String.format("Failed to get bean properties on (%s)", clazz), e);
        }
        return newHashSet();
    }

    @VisibleForTesting
    BeanInfo getBeanInfo(Class<?> clazz) throws IntrospectionException {
        return Introspector.getBeanInfo(clazz);
    }

}